Northern Prairie Wildlife Research Center
Western Wetland Flora
Field Office Guide to Plant Species
Vallisneria americana Michx.
- Family: Frog's-bit (Hydrocharitaceae)
- Flowering: July-September
- Field Marks: This distinctive plant is recognized by its long, submerged, ribbon-like leaves that are minutely toothed along the edges.
- Habitat: Shallow waters of lakes and streams.
- Habit: Aquatic perennial herb with stolons.
- Stems: Slender, smooth stolons.
- Leaves: Elongated and ribbon-like, up to 3 feet long, up to 1/3 inch wide, without hairs, minutely toothed along the edges, partially septate.
- Flowers: Male and female flowers borne on separate plants; male flowers numerous,
crowded, subtended by a bract (spathe), breaking free while in bud and floating to the water
surface on a long stalk before opening; female flowers solitary and sessile in a tubular spathe.
- Sepals: 3, free from each other, greenish, ovate, pointed at the tip.
- Petals: 1 in the male flower, smaller than the sepals; 3 in the female flower, nearly transparent.
- Stamens: 2, the filaments united; a third sterile stamen is present, resembling a petal.
- Pistils: Ovary inferior; stigmas 3.
- Fruits: Indehiscent, ripening under water as the stalk becomes coiled and pulls the fruit below the water surface; seeds with conspicuous cross-markings.
- Notes: This species is sometimes known as eelgrass. It has the ability to clog up shallow water when it develops into dense colonies. The leaves provide cover for fish. There is an apparent erroneous report of this plant from Colorado.
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